Experiments in this project are designed to define those human leukocyte interactions that are characteristic of immune dysfunctions occurring after trauma or concomitant with injury. The in vitro generation of antibody forming cells (AFC) is utilized as a measure of specific human leukocyte immunocompetence. Those regulatory interactions between normal leukocyte populations which attenuate or augment induction of immune responses are being defined. The leukocytes of trauma patients are being sequentially studied after injury. Any immune dysfunction in the interactions of thymus derived (T) cells, bursal equivalent (B) cells and/or monocytes are being assessed in the AFC system.